Note: Descriptions are shown in the official language in which they were submitted.
CA 02880205 2015-01-28
WEAR ASSEMBLY FOR EXCAVATING EQUIPMENT
This application is a divisional application of Canadian Patent File No.
2,686,620 filed May 6, 2008 from PCT Application No. PCT/US2008/062724.
Field of the Invention
[01] The present invention pertains to a wear assembly for securing a wear
member to excavating equipment, and in particular to a wear assembly that is
well
suited for attachment and use on a dredge cutterhead.
Background of the Invention
[02] Dredge cutterheads are used for excavating earthen material that is
underwater, such as a riverbed. In general, a dredge cutterhead 1 includes
several
arms 2 that extend forward from a base ring 3 to a hub 4 (Fig. 21). The arms
are
spaced about the base ring and formed with a broad spiral about the central
axis of
the cutterhead. Each arm 2 is provided with a series of spaced apart teeth 5
to dig
into the ground. The teeth are composed of adapters or bases 6 that are fixed
to
the arms, and points 7 that are releasably attached to the bases by locks 8.
[03] In use, the cutterhead is rotated about its central axis to excavate
the
earthen material. A suction pipe is provided near the ring to remove the
dredged
material. To excavate the desired swath of ground, the cutterhead is moved
side-to-
side as well as forward. On account of swells and other movement of the water,
the
cutterhead also tends to move up and down, and periodically impact the bottom
surface. Further difficulties are caused by the operator's inability to see
the ground
that is being excavated underneath the water; i.e., unlike most other
excavating
operations, the dredge cutterhead cannot be effectively guided along a path to
best
suit the terrain to be excavated. In view of the heavy loads and severe
environment,
the point and base interconnection needs to be stable and secure.
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[04] The cutterheads are rotated such that the teeth are driven into and
through the ground at a rapid rate. Consequently, considerable power is needed
to
drive the cutterhead, particularly when excavating in rock. In an effort to
minimize
the power requirements, dredge points are typically provided with elongate,
slender
bits for easier penetration of the ground. However, as the bit becomes shorter
due
to wear, the mounting sections of the points will begin to engage the ground
in the
cutting operation. The mounting section is wider than the bit and is not
shaped for
reduced drag. On account of the resulting increased drag the mounting sections
impose on the cutterhead, the points are usually changed at this time before
the bits
are fully worn away.
Summary of the Invention
[05] In accordance with one aspect of the invention, a wear member for
excavating equipment is formed with side relief in the working and mounting
sections to minimize the drag associated with the digging operation and, in
turn,
minimize the power needed to drive the equipment. Reduced power consumption,
in turn, leads to a more efficient operation and a longer usable life for the
wear
member.
[06] In accordance with the invention, the wear member has a transverse
configuration where the width of the leading side is larger than the width of
the
corresponding trailing side so that the sidewalls of the wear member follow in
the
shadow of the leading side to decrease drag. This use of a smaller trailing
side is
provided not only through the working end but also at least partially into the
mounting end. As a result, the drag experienced by a worn wear member of the
invention is less than that of a conventional wear member. Less drag
translates into
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less power consumption and a longer use of the wear member before it needs to
be
replaced. Accordingly, the working ends of the wear member can be further worn
away before replacement is needed.
[07] In accordance with another aspect of the invention, the wear member
has a digging profile that is defined by the transverse configuration of that
portion of
the wear member that penetrates the ground in one digging pass and in the
direction of motion through the ground. In one other aspect of the present
invention,
side relief in the wear member is provided in the digging profile to lessen
the drag
experienced during a digging operation. In a preferred embodiment, side relief
is
provided in every digging profile expected through the life of the wear member
including those which encompass the mounting section.
[08] In another aspect of the invention, the wear member includes a socket
for receiving a nose of a base fixed to the excavating equipment. The socket
is
formed with a generally trapezoidal transverse shape that generally
corresponds to
the transverse trapezoidal exterior profile of the wear member. This general
matching of the socket to the exterior of the mounting section eases
manufacture,
maximizes the size of the nose, and enhances the strength to weight ratio.
[09] In a preferred construction, one or more of the top, bottom or side
surfaces of a trapezoidal shaped nose and the corresponding walls of the
socket are
each bowed to fit together. These surfaces and walls have a gradual curvature
to
ease installation, enhance stability of the wear member, and resist rotation
of the
wear member about the longitudinal axis during use.
[10] In accordance with another aspect of the invention, the socket and
nose each includes rear stabilizing surfaces that extend substantially
parallel to the
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longitudinal axis of the wear member and substantially around the perimeter of
the
socket and nose to resist rearward loads applied in all directions.
[11] In accordance with another aspect of the invention, the socket and
nose are formed with complementary front bearing faces that are substantially
hemispherical to lessen stress in the components and to better control the
rattle that
occurs between the wear member and the base.
[12] In another aspect of the invention, the socket and nose are formed
with front curved bearing faces at their front ends, and with generally
trapezoidal
transverse shapes rearward of the front ends to improve stability, ease
manufacture,
maximize the size of the nose, reduce drag, stress and wear, and enhance the
strength to weight ratio.
[13] In accordance with another aspect of the invention, the wear assembly
includes a base, a wear member that mounts to the base, and an axially
oriented
lock that in a compressive state holds the wear member to the base in a manner
that is secure, easy to use, readily manufactured, and can tighten the fit of
the wear
member on the base. In one preferred embodiment, the wear assembly includes an
adjustable axial lock.
[14] In another aspect of the invention, the wear member includes an
opening into which the lock is received, and a hole that is formed in a rear
wall of
the opening to accommodate passage of a lock to stabilize the lock and
facilitate
easy tightening of the lock.
[15] In another aspect of the invention, the base interacts with the lock
solely through the use of a projecting stop. As a result, there is no need for
a hole,
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recess or passage in the nose such as is typically provided to receive the
lock. The
nose strength is thus enhanced.
[16] In another aspect of the invention, the locking arrangement for
securing the wear member to the base can be adjusted to consistently apply a
predetermined tightening force to the wear member irrespective of the amount
of
wear that may exist in the base and/or wear member.
[17] In another aspect of the invention, the wear member includes a marker
that can be used to identify when the lock has been adequately tightened.
[18] In another aspect of the invention, the wear member is installed and
secured to the base through an easy to use, novel process involving an axial
lock.
The wear member fits over a nose of a base fixed to the excavating equipment.
The
base includes a stop that projects outward from the nose. An axial lock is
received
into an opening in the wear member and extends between the stop and a bearing
surface on the wear member to releasably hold the wear member to the nose.
[19] In another aspect of the invention, the wear member is first slid over
a
base fixed to the excavating equipment. An axially oriented lock is positioned
with
one bearing face against a stop on the base and another bearing face against a
bearing wall on the wear member such that the lock is in axial compression.
The
lock is adjusted to move the wear member tightly onto the base.
[20] In another aspect of the invention, a lock to releasably hold a wear
member to a base includes a threaded linear shaft, with a bearing end and a
tool
engaging end, a nut threaded onto the shaft, and a spring including a
plurality of
alternating annular elastomeric disks and annular spacers fit about the
threaded
shaft between the bearing end and the nut.
CA 02880205 2015-01-28
[20a] In another aspect, the invention contemplates a wear member for
excavating equipment comprising a working section and a mounting section
aligned
along a longitudinal axis. The mounting section includes a socket for
receiving a
base fixed to the excavating equipment, and an opening in communication with
the
socket for receiving a lock in an axial direction to releasably hold the wear
member to
the excavating equipment. The opening has a front wall and a rear wall. The
rear
wall defines a surface to maintain the lock in a compressive state and the
rear wall
includes a hole through which the lock extends from the opening at an
inclination to
the longitudinal axis for easy access outside of the opening by an operator
for
tightening of the lock.
[20b1 In another aspect, the invention contemplates a wear assembly for
excavating equipment that includes a base fixed to the excavating equipment
including a first surface, a wear member including a working section and a
mounting
section aligned along a longitudinal axis where the mounting section has a
socket in
which to receive the base and an opening having a second surface, and an
elongate
lock oriented in the same direction as the longitudinal axis to fit between
the first
surface and the second surface in a compressive state to releasably hold the
wear
member to the base. The lock includes a first face to contact the first
surface on the
base and a second face to contact the second surface on the wear member. The
first and second surfaces are aligned and face in opposite directions and the
lock is
adjustable such that the first and second faces can be moved apart when
contacting
the first and second surfaces to tighten the fit of the lock between the
components
and tighten the fit of the wear member onto the base.
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[20c] In another aspect, the invention contemplates a wear assembly for
excavating equipment that includes a base fixed to the excavating equipment
that
includes a first surface, a wear member with a working section and a mounting
section aligned along a longitudinal axis where the mounting section has a
socket in
which to receive the base and an opening having a second surface, and an
elongate
lock oriented in the same direction as the longitudinal axis to fit between
the first
surface and the second surface in a compressive state to releasably hold the
wear
member to the base. The lock includes a threaded shaft to bear against the
first
surface, a nut threaded to the shaft, and a spring about the shaft to be
compressed
between the second surface and the nut.
[20d] In another aspect, the invention contemplates a method for installing
a
wear member onto excavating equipment that includes fitting a wear member with
a
socket over a nose fixed to the excavating equipment such that the nose is
received
into the socket, positioning an elongate lock in an opening in the wear member
so
that a first bearing surface of the lock fits against a bearing surface on the
nose, a
second bearing surface of the lock fits against a bearing surface on the wear
member and a longitudinal axis of the lock is oriented in the direction the
wear
member is fit over the nose, adjusting the lock with first bearing surfaces
fit against
the nose and the second bearing surface fit against the wear member to tighten
the
fit of the wear member onto the nose so that the lock is in a compressive
state to
hold the wear member to the base.
[20e] In another aspect, the invention contemplates a method for installing
a
wear member onto excavating equipment that includes fitting a wear member with
a
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socket over a nose fixed to the excavating equipment such that the nose is
received
into the socket, positioning an elongate lock in an opening in the wear member
so
that a first bearing surface of the lock fits against a bearing surface on the
nose, a
second bearing surface of the lock fits against a bearing surface on the wear
member and a longitudinal axis of the lock is oriented in the direction the
wear
member is fit over the nose, adjusting the lock to tighten the fit of the wear
member
onto the nose so that the lock is in a compressive state to hold the wear
member to
the base. The lock includes a threaded shaft to bear against the first
surface, a nut
threaded to the shaft and a spring about the shaft to be compressed between
the
second surface and the nut.
[20f] In another aspect, the invention contemplates a method for installing
a
wear member onto excavating equipment that includes providing a nose fixed to
the
excavating equipment having a stop that projects outward from one side
thereof,
fitting the wear member with a socket over the nose so that an opening
extending
through the wear member is placed in axial alignment with the stop rearward of
the
stop, inserting a lock into the opening and in a hole in the wear member to
extend
out of the opening and outward of the nose and along an exterior side of the
nose to
abut against the stop and a wall of the opening to releasably hold the wear
member
to the nose.
[20g] In another aspect, the invention contemplates a method for installing
a
point onto an adapter secured to excavating equipment that includes fitting
the point
with a socket defined by a top wall, a bottom wall and sidewalls over a
forwardly
projecting nose fixed to the excavating equipment such that the nose is
received into
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the socket, then positioning an elongate lock having a threaded shank in an
opening
in the point where the lock extends axially through the opening so that a
front end of
the lock fits against a stop on the nose, and then positioning a nut threaded
to the
shank, adjusting the lock to move the nut along the length of the shank in a
rearward
direction relative to the nose such that the nut abuts a rear wall of the
opening and a
front bearing face in the socket of the point is tightened against a forward-
facing
bearing face of the nose.
[20h] In another aspect, the invention contemplates a wear assembly for
excavating equipment that includes a base fixed to the excavating equipment
and
including a stop, a wear member including a working section and a mounting
section
aligned along a longitudinal axis where the mounting section includes a socket
for
receiving the base fixed to the excavating equipment and an opening rearward
of the
stop in communication with the socket for receiving a lock to releasably hold
the
wear member to the excavating equipment. The opening has a front wall and a
rear
wall where the rear wall includes a hole. There is a lock which abuts the stop
and
extends through the hole at an inclination to the longitudinal axis for easy
access by
an operator for tightening of the lock.
[20i] In another aspect, the invention contemplates a wear assembly for
excavating equipment that includes a base fixed to the excavating equipment
and a
wear member received over a portion of the base. The portion of the base
received
within the wear member includes a laterally-outward projecting stop and is
substantially solid throughout. The wear member includes an opening having a
rear
wall and a lock that extends rearward and is inclined to the longitudinal
axis. The
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lock includes a threaded shank with a front end to contact the stop and a nut
that
applies a biasing force on the rear wall of the opening to releasably hold the
wear
member to the base.
[20j] In another aspect, the invention contemplates a wear assembly that
includes a wear member with a front working portion, a socket at the rear and
an
opening in the wear member in communication with the socket including a front
edge
and a rear bearing surface. A base is configured to receive the socket of the
wear
member aligned along a longitudinal axis. The base includes a front bearing
surface.
There is a lock includes a front end and a rear end to engage the front
bearing
surface and the rear bearing surface where with the lock, positioned in the
opening
and in a compressive state, biases the lock front end against the front
bearing
surface of the base and the lock rear end against the rear bearing surface of
the
wear member to secure the wear member to the base.
[20k] In another aspect, the invention contemplates a wear member for
excavating equipment that includes a working section and a mounting section
aligned along a longitudinal axis. The mounting section includes a socket for
receiving a base fixed to the excavating equipment. There is an opening in
communication with the socket for receiving a lock in an axial direction to
releasably
hold the wear member to the excavating equipment. The opening has a front wall
and a rear wall where the rear wall includes a hole through which the lock
extends
from the opening at an inclination to the longitudinal axis so that the lock
abuts a stop
on the nose within the socket and for easy access outside of the opening by an
operator for tightening of the lock.
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Brief Description of the Drawings
[21] Figure 1 is a wear assembly in accordance with the present invention.
[22] Figure 2 is a side view of a wear member of the invention.
[23] Figure 2A is a side view of a conventional wear member.
[24] Figure 3 is a cross-sectional view taken along line 3-3 in Figure 2.
[25] Figure 3A is a cross-sectional view taken along line 3A-3A in Figure
2A.
[26] Figure 4 is a cross-sectional view taken along line 4-4 in Figure 2.
[27] Figure 5 is a cross-sectional view taken along line 5-5 in Figure 2.
[28] Figure 6 is a cross-sectional view taken along line 6-6 in Figure 2.
[29] Figure 6A is the cross-sectional view taken along line 6A-6A in Figure
2A.
[30] Figure 7 is a cross-sectional view taken along line 7-7 in Figure 2.
[31] Figure 8 is a cross-sectional view taken along line 8-8 in Figure 2.
[32] Figure 9 is a cross-sectional view taken along line 9-9 in Figure 1.
[33] Figure 10 is a top view of the wear member.
[34] Figure 11 is a rear view of the wear member.
[35] Figure 12 is a perspective view of a nose of a base of the invention.
[36] Figure 13 is a front view of the nose.
[37] Figure 14 is a side view of the nose.
[38] Figure 15 is an enlarged perspective view of a lock in the wear
assembly.
[39] Figure 16 is an enlarged perspective view of the lock in the wear
assembly prior to tightening.
[40] Figure 17 is a perspective view of the lock.
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[41] Figure 18 is a side view of the lock.
[42] Figure 19 is an exploded, perspective view of the lock.
[43] Figure 20 is a perspective view of the lock with the nose (the point
has
been omitted).
[44] Figure 21 is a side view of a conventional dredge cutterhead.
Detailed Description of the Preferred Embodiments
[45] The present invention pertains to a wear assembly 10 for excavating
equipment, and is particularly well suited for dredging operations.
In this
application, the invention is described in terms of a dredge tooth adapted for
attachment to a dredge cutterhead. Nevertheless, the different aspects of the
invention can be used in conjunction with other kinds of wear assemblies
(e.g.,
shrouds) and for other kinds of excavating equipment (e.g., buckets).
[46] The assembly is at times described in relative terms such as up, down,
horizontal, vertical, front and rear; such terms are not considered essential
and are
provided simply to ease the description. The orientation of a wear member in
an
excavating operation, and particularly in a dredge operation, can change
considerably. These relative terms should be understood with reference to the
orientation of wear assembly 10 as illustrated in Figure 1 unless otherwise
stated.
[47] Wear assembly 10 includes a base 12 secured to a dredge
cutterhead, a wear member 14, and a lock 16 to releasably hold the wear member
to base 12 (Figs. 1-10).
[48] Base 12 includes a forwardly projecting nose 18 onto which wear
member 14 is mounted, and a mounting end (not shown) that is fixed to an arm
of a
dredge cutterhead (Figs. 1, 9 and 11-14). The base may be cast as part of the
arm,
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welded to the arm, or attached by mechanical means. As examples only, the base
may be formed and mounted to the cutterhead such as disclosed in U.S. Patent
No.
4,470,210 or U.S. Patent No. 6,729,052.
[49] In a dredge tooth, wear member 14 is a point provided with a working
section 21 in the form of an elongate slender bit and a mounting section 23
that
defines a socket 20 to receive nose 18 (Figs. 1-10). Point 14 is rotated by
the
cutterhead such that it engages the ground in generally the same way with each
digging pass. As a result, point 14 includes a leading side 25 and a trailing
side 27.
Leading side 25 is the side that first engages and leads the penetration of
the
ground with each rotation of the cutterhead. In the present invention,
trailing side 27
has a smaller width than leading side 25 (i.e., along a plane perpendicular to
the
longitudinal axis 28 of point 14) through bit 21 (Fig. 5) and at least
partially through
mounting section 23 (Fig. 4). In a preferred embodiment, trailing side 27 has
a
smaller width than leading side 25 throughout the length of point 14 (Figs. 4,
5 and
7).
[50] Bit 21 of point 14 preferably has a generally trapezoidal transverse
configuration with a leading side 25 that is wider than trailing side 27 (Fig.
5). The
term "transverse configuration" is used to refer to the two-dimensional
configuration
along a plane perpendicular to the longitudinal axis 28 of wear member 14. On
account of this narrowing of the point, sidewalls 29, 31 follow in the shadow
of
leading side 25 during digging and thereby create little drag on the cutting
operation.
In a preferred construction, sidewalls 29, 31 converge toward trailing side 27
at an
angle 0 of about 16 degrees (Fig. 5); however, other angular configurations
are
possible. The leading side 25, trailing side 27 and sidewalls 29, 31 can be
planar,
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curved or irregular. Moreover, shapes other than trapezoidal can be used that
provide side relief.
[51] In use, dredge point 14 penetrates the ground to a certain depth with
each digging pass (i.e., with each rotation of the cutterhead). During much of
the
point's useful life, the bit alone penetrates the ground. As one example, the
ground
level in one digging cycle extends generally along line 3-3 (Fig. 2) at the
center point
of a digging pass. Since only the bit penetrates the ground and the bit is
relatively
thin, the drag placed on the digging operation is within manageable limits.
Nevertheless, with many teeth being constantly driven through the ground at a
rapid
rate, power requirements are always high and reducing the drag even in the bit
is
beneficial to the operation, especially when digging through rock.
[52] In a preferred construction, sidewalls 29, 31 not only converge toward
trailing side 27, but are configured so that the sidewalls lie within the
shadow of the
leading side 25 in the digging profile. The "digging profile" is used to mean
the
cross-sectional configuration of the portion of point 14 that penetrates the
ground
along a plane that is (i) parallel to the direction of travel 34 at the center
point of a
digging pass through the ground and (ii) laterally perpendicular to the
longitudinal
axis. The digging profile is a better indication of the drag to be imposed on
the point
during use than a true transverse cross section. The provision of side relief
in the
digging profile is dependent on the angle at which the sidewalls converge
toward the
trailing side and the axial slope or expansion of the point surfaces in a
rearward
direction. The intention is to provide a width that generally narrows from the
leading
side to the trailing side when considered from the perspective of the digging
profile.
Side relief in the digging profile preferably extends across the expected
cutterhead
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,
,
digging angles, but benefit can still be obtained if such side relief exists
in at least
one digging angle. As one example only, the cross-sectional configuration
illustrated in Figure 3 represents one digging profile 35 for a portion of
point 14
being driven through the ground. As can be seen, bit 21 is still provided with
side
relief even in the digging profile as sidewalls 29, 31 converge toward
trailing side 27
for reduced drag.
[53] As bit 21 wears away, the ground level gradually creeps rearward so
that more rearward, thicker portions of the point 14 are pushed through the
ground
with each digging cycle. More power is therefore required to drive the
cutterhead as
the points wear. Eventually, enough of the bit wears away such that the
mounting
section 23 of the point 14 is being driven through the ground with each
digging pass.
In the present invention, the mounting section 23 continues to include side
relief at
least at the front end 40 of the mounting section (Fig. 4), and preferably
throughout
the mounting section (Figs. 4 and 7). As seen in Figure 4, mounting section 23
is
larger than bit 21 to accommodate the receipt of nose 18 into socket 20 and to
provide ample strength for the interconnection between point 14 and base 12.
Sidewalls 29, 31 are inclined so as to converge toward trailing side 27. The
inclination of sidewalls 29, 31 along line 4-4 is, in this one example, at an
angle a of
about 26 degrees (Fig. 4), but other inclinations can also be used. As
discussed
above, the desired side relief in the digging profile depends on the relation
between
the transverse inclination of the sidewalls and the axial expansion of the
point.
[54] In one conventional point 14a, bit 21a has a trapezoidal transverse
configuration with a leading side 25a that is wider than trailing side 27a.
However,
bit 21a does not provide side relief in the digging profile. As seen in Figure
3A, the
CA 02880205 2015-01-28
digging profile 35a (i.e. along line 3A-3A) in Figure 2A does not have
sidewalls 29a,
31a that converge toward trailing side 27a (Figs. 2A and 3A). Rather,
sidewalls 29a,
31a in digging profile 35a expand outward at an increasingly greater slope as
the
sidewalls extend toward the trailing side. This outward flaring of sidewalls
29a, 31a
will generate an increased drag on the cutterhead. The effective use of side
relief in
point 14 for the digging profile is a better reduction of drag than simply
using
sidewalls that convey in a transverse configuration.
[55] In one
other example, bit 21 has worn down to an extent where the
portion of mounting section 23 along line 6-6 (Figs. 2 and 6) is driven
through the
ground. Even the mounting section 23 provides side relief for reduced drag;
i.e.,
sidewalls 29, 31 converge toward trailing side even in digging profile 45. The
presence of side relief in digging profile 45 imposes less drag and, hence,
requires
less power to be driven through the ground. The reduced drag, in turn, enables
the
cutterhead to continue to operate with points worn to the point where the
mounting
section penetrates the ground. In conventional point 14a, mounting section 23a
does not have a trapezoidal transverse configuration with sidewalls 29a, 31a
that
converge toward trailing side 27a. Moreover, as seen in Figure 6A, sidewalls
29a,
31a diverge from leading side 25a in digging profile 45a taken along line 6a-
6a
encompassing the front end 40a of mounting section 23a. The lack of side
relief in
the digging profile imposes a heavy drag on the point 14a as it is driven
through the
ground especially as compared to the present inventive point 14. With the
heavy
drag produced by points 14a in this condition, many operators will replace the
points
when the mounting sections 23a begin to be driven through the ground even
though
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bits 21a are not fully worn out. With the present invention, points 14 can
stay on
bases 12 until bits 21 are further worn out.
[56] In a preferred construction, the tapering of sidewalls 29, 31
continues
from front end 37 to rear end 47 of point 14. As seen in Figure 7, sidewalls
29, 31
converge toward trailing side 27 even at the rear of mounting section 23.
Moreover,
side relief is provided even in a digging profile 55 along line 8-8 (Figs. 2
and 8), i.e.,
sidewalls 29, 31 converge toward trailing side 27 even in this rearward
digging
profile 55.
[57] The use of a point 14 with side relief in bit 21 and mounting end 23
as
described above can be used with virtually any nose and socket configuration.
Nonetheless, in one preferred construction, front end 58 of nose 18 includes a
forward-facing bearing face 60 that is convex and curved about two
perpendicular
axes (figs. 1, 9 and 11-14). Likewise, the front end 62 of socket 20 is formed
with a
complementary concave and curved bearing face 64 to set against bearing face
60
(Figs. 1, 7, 9 and 11). In the illustrated construction, front bearing faces
60, 64 each
conforms to a spherical segment to lessen stress in the components due to the
application of non-axial loads such as disclosed in US Patent No. 6,729,052,
which
may be referred to for further details.
[58] Preferably, front ends 58, 62 are each generally hemispherical to
reduce the rattle between point 14 and base 12 and more effectively resist
loads
from all directions. Front bearing surface 64 of socket 20 is preferably
slightly
broader than hemispherical at its ends and center to accommodate reliably
mounting of points 14 on different bases (i.e., without binding or bottoming
out), but
which under common loads or following wear operate as a true hemispherical
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socket surface on the hemispherical ball surface of base 12. In a conventional
tooth
10a (Fig. 2A), the point shifts 14a around on the nose as the tooth is forced
through
the ground. The front ends of the socket and nose are angular with flat
bearing
surfaces and hard corners. During use, point 14a shifts around on the nose
such
that the front of the socket 20a rattles around and against the front end of
the nose,
and the rear end of the socket shifts around and rattles against the rear end
of the
nose. This shifting and rattling causes the point and base to wear. In the
present
invention, the use of generally hemispherical front bearing faces 60, 64
substantially
reduces the rattle at the front end of the socket 20 and nose 18 (Figs. 1 and
9).
Rather, the use of smooth, continuous front bearing faces enables the point to
roll
about the nose to reduce wear. A small band 65, substantially parallel to the
longitudinal axis 28, preferably extends directly rearward of the generally
hemispherical bearing surfaces to provide additional capacity for the nose to
wear
and still maintain the desired support. The term "substantially parallel" is
intended to
include parallel surfaces as well as those that axially diverge rearwardly
from axis
28 at a small angle (e.g., of about 1-7 degrees) for manufacturing or other
purposes.
The small band 65 Is preferably axially inclined no more than 5 degrees to
axis 28,
and most preferably is axially inclined about 2-3 degrees.
[59] Nose 18 includes a body 66 rearward of front end 58
(Figs. 11-14).
Body 66 is defined by an upper surface 68, a lower surface 69 and side
surfaces 70,
71. In a preferred construction, body surfaces 68-71 diverge rearwardly so
that
nose 18 expands outward from front end 58 to provide a more robust nose to
withstand the rigors of digging. Nevertheless, it is possible for only the
upper and
lower surfaces 68, 69 to diverge from each other and for the side surfaces 70,
71 to
13
= CA 02880205 2015-01-28
axially extend substantially parallel to each other. Socket 20 has a main
portion 76
rearward of front end 62 to receive body 66. Main portion 76 includes an upper
wall
78, lower wall 79 and sidewalls 80, 81 that conform to body surfaces 68-71. In
a
preferred embodiment, body 66 and main portion 76 each have a trapezoidal
transverse configuration. The use of a trapezoidal shape predominantly along
the
length of nose 18 and socket 20 provides four corners 67, 77, which act as
spaced
ridges to resist turning of wear member 14 about axis 28.
[60] Also, in a preferred embodiment, at least one of the body surfaces 68-
71 and socket walls 78-81 (and preferably all of them) have mutually bowed
configurations (Figs. 7, 11 and 13); that is, body surfaces 68-71 are
preferably
concave and curved across substantially their entire widths to define a trough
84 on
each of the four sides of body 66. Likewise, socket walls 78-81 are preferably
convex and curved across substantially their entire widths to define
projections 86
received into troughs 84. The preferred bowing of nose surfaces 68-71 and
socket
walls 78-81 across substantially their entire widths accentuate corners 67, 77
to
provide increased resistance to the rotation of point 14 about base 12 during
operation. The troughs and projections will also reduce rotational rattle of
the point
on the base. While the bowed surfaces 68-71 and walls 78-81 are preferred,
other
trough and projection configurations could also be used. Other rotation
resisting
constructions could also be used.
[61] The use of troughs 84 and projections 86, and particularly those that
are gradually curved and extending substantially across the entire widths of
the
surfaces 68-71 and walls 78-81 eases the assembly of point 14 onto nose 18;
i.e.,
14
== CA 02880205 2015-01-28
the troughs 84 and projections 86 cooperatively direct point 14 into the
proper
assembled position on nose 18 during assembly. For example, if point 14 is
initially
installed on nose 18 out of proper alignment with the nose as it is fit onto
the nose,
the engagement of projections 86 being received into the troughs 84 will tend
to
rotate the point into proper alignment as the point is fed rearward onto nose
18.
This cooperative effect of troughs 84 and projections 86 greatly eases and
speeds
installation and the setting of corners 67 into corners 77. Some variations
could
also be used between the shapes of the socket and the nose so long as the
socket
predominantly matches the shape of the nose.
[62] Nose surfaces 68-71 with troughs 84 are each
preferably inclined
axially to expand outward as they extend rearward to provide strength to nose
18
until reaching a rear stabilizing surface 85 of nose 18. Likewise, socket
walls 78-81
with projections 86 also each expand to conform to surfaces 68-71. Socket
walls
78-81 also define rear stabilizing surfaces 95 to bear against stabilizing
surfaces 85.
Rear stabilizing surfaces 85, 95 are substantially parallel to longitudinal
axis 28. In
one preferred embodiment, each stabilizing surface 85, 95 diverges axially
rearward
at an angle to axis 28 of about 7 degrees. The rear stabilizing surfaces 85,
95 also
preferably encircle (or at least substantially encircle) nose 18 and socket 20
to better
resist non-axial loads. While contact between the various socket surfaces and
the
nose will likely occur during an excavating operation, contact between the
corresponding front bearing surfaces 60, 64 and rear stabilizing surfaces 85,
95 is
intended to provide primary resistance to the applied loads on the tooth and
thereby
provide the desired stability. While stabilizing surfaces 85, 95 are
preferably formed
with short axial extensions, they could have longer or different
constructions. Also,
= CA 02880205 2015-01-28
,=.
in certain circumstances, e.g., in light duty operations, benefits can be
achieved
without stabilizing surfaces 85, 95.
[63] Front bearing faces 60, 64 and rear stabilizing surfaces 85, 95 are
provided to stabilize the point on the nose and to lessen stress in the
components.
The generally hemispherical bearing faces 60, 64 at the front ends 58, 62 of
the
nose 18 and socket 20 are able to stably resist axial and non-axial rearward
forces
in direct opposition to the loads irrespective of their applied directions.
This use of
curved, continuous front bearing surfaces reduces rattling of the point on the
nose
and reduces the stress concentrations that otherwise exist when corners are
present. Rear stabilizing surfaces 85, 95 complement the front bearing faces
60, 64
by reducing the rattle at the rear of the point and providing stable
resistance to the
rear portions of the point, as described in U.S. Patent No. 5,709,043 which
may be
referred to for further details. With stabilizing surfaces 85, 95 extending
about the
entire perimeter of nose 18 or at least substantially about the entire
perimeter (Figs.
7, 9 and 11-14), they are also able to resist the non-axially directed loads
applied in
any direction.
[64] Main portion 76 of socket 20 preferably has a generally trapezoidal
transverse configuration to receive a matingly shaped nose 18 (Figs. 7 and
11).
The generally trapezoidal transverse configuration of socket 20 generally
follows the
generally trapezoidal transverse configuration of the exterior 97 of point 14.
This
cooperative shaping of the socket 20 and exterior 97 maximizes the size of the
nose
18 that can be accommodated within point 14, eases the manufacturing of point
14
in a casting process, and enhances the strength to weight ratio.
16
CA 02880205 2015-01-28
[65] A wide variety of different locks can be used to releasably secure
wear
member 14 to base 12. Nonetheless, in a preferred embodiment, lock 16 is
received into an opening 101 in wear member 14, preferably formed in trailing
wall
27 though it could be formed elsewhere (Figs. 1, 9 and 15-20). Opening 101
preferably has an axially elongated shape and includes a front wall 103, a
rear wall
105, and sidewalls 107, 109. A rim 111 is built up around opening 101 for
protection
of the lock and for additional strength. Rim 111 is also enlarged along rear
wall 105
to extend farther outward of exterior surface 97 and define a hole 113 for
passage of
lock 16. The hole stabilizes the position of lock 16 and permits easy access
to it by
the operator.
[66] Nose 18 includes a stop 115 that projects outward from upper side 68
of nose 18 to engage lock 16. Stop 115 preferably has a rear face 119 with a
concave, curved recess 121 into which a front end 123 of lock 16 is received
and
retained during use, but other arrangements could be used to cooperate with
the
lock. In a preferred construction, opening 101 is long enough and trailing
wall 27
sufficiently inclined to provide clearance for stop 115 when wear member 14 is
installed onto nose 18. Nevertheless, a relief or other forms of clearance
could be
provided in socket 20 if needed for the passage of stop 115. Further, the
projection
of stop 115 is preferably limited by the provision of a depression 118 to
accommodate a portion of lock 16.
[67] Lock 16 is a linear lock oriented generally axially to hold wear
member
14 onto base 12, and to tighten the fit of wear member 14 onto nose 18. The
use of
a linear lock oriented axially increases the capacity of the lock to tighten
the fit of the
wear member on the nose; i.e., it provides for a greater length of take up. In
a
17
, CA 02880205 2015-01-28
. ,
,
preferred embodiment, lock 16 includes a threaded shaft 130 having a front end
123
and a rear end with head 134, a nut 136 threaded to shaft 130, and a spring
138
(Figs. 1, 9 and 15-20). Spring 138 is preferably formed of a series of
elastomeric
disks 140 composed of foam, rubber or other resilient material, separated by
spacers 142 which are preferably in the form of washers. Multiple disks 140
are
used to provide sufficient force, resiliency and take up. The washers isolate
the
elastonneric disks so that they operate as a series of individual spring
members.
Washers 142 are preferably composed of plastic but could be made of other
materials. Moreover, the spring of the preferred construction is economical to
make
and assemble on shaft 130. Nevertheless, other kinds of springs could be used.
A
thrust washer 142a or other means is preferably provided at the end of the
spring to
provide ample support.
[68] Shaft 130 extends centrally through spring 138 to
engage nut 136.
Front end 123 of shaft 130 fits into recess 121 so that the shaft 130 is set
against
stop 115 for support. Rear end 134 of lock 16 extends through hole 113 in wear
member 14 to enable a user to access the lock outside of opening 101. The
shaft is
preferably set at an angle to axis 28 so that head 134 is more easily
accessed.
Spring 138 sets between rear wall 105 and nut 136 so that it can apply a
biasing
force to the wear member when the lock is tightened. Hole 113 is preferably
larger
than head 134 to permit its passage during installation of lock 16 into
assembly 10.
Hole 113 could also be formed as an open slot to accommodate insertion of
shaft
130 simply from above. Other tool engaging structures could be used in lieu of
the
illustrated head 134.
18
, CA 02880205 2015-01-28
[69] In use, wear member 14 is slid over nose 18 so that nose 18 is fit
into
socket 20 (Figs. 1 and 9). The lock can be temporarily held in hole 113 for
shipping,
storage and/or installation by a releasable retainer (e.g., a simple twist
tie) fit around
shaft 130 outside of opening 101 or it can be installed after the wear member
is fit
onto the nose. In any event, shaft 130 is inserted through hole 113 and its
front end
123 set in recess 121 of stop 115. Lock 16 is positioned to lie along the
exterior of
nose 18 so that no holes, slots or the like need to be formed in the nose to
contain
the lock for resisting the loads. Head 134 is engaged and turned by a tool to
tighten
the lock to a compressive state to hold the wear member; i.e., shaft 130 is
turned
relative to nut 136 so that front end 123 presses against stop 115. This
movement,
in turn, draws nut 136 rearward against spring 138, which is compressed
between
nut 136 and rear wall 105. This tightening of lock 16 pulls wear member 14
tightly
onto nose 18 (i.e., with front bearing faces 60, 64 engaged) for a snug fit
and less
wear during use. Continued turning of shaft 130 further compresses spring 138.
The compressed spring 138 then urges wear member 14 rearward as the nose and
socket begin to wear. The stability of the preferred nose 18 and point 14
enables
the use of an axial lock, i.e., no substantial bending forces will be applied
to the lock
so that the high axial compressive strength of the bolt can be used to hold
the wear
member to the base. Lock 16 is lightweight, hammerless, easy to manufacture,
does not consume much space, and does not require any openings in the nose.
[70] In a preferred construction, lock 16 also includes an indicator 146
fit
onto shaft 130 in association with nut 136 (Figs. 15-20). Indicator 146 is
preferably
a plate formed of steel or other rigid material that has side edges 148, 149
that fit
closely to sidewalls 107, 109 of opening 101, but not tightly into opening
101.
19
= , ' . CA 02880205 2015-01-28
Indicator 146 includes an opening that fully or partially receives nut 136 to
prevent
rotation of the nut when shaft 130 is turned. The close receipt of side edges
148,
149 to sidewalls 107, 109 prevents indicator 146 from turning. Alternatively,
the
indicator could have a threaded bore to function as the nut; if the indicator
were
omitted, other means would be required to hold nut 136 from turning. Indicator
146
could also be discrete from nut 136.
[71] Indicator 146 provides a visual indication of when shaft 130 has been
suitably tightened to apply the desired pressure to the wear member without
placing
undue stress on shaft 130 and/or spring 138. In a preferred construction,
indicator
146 cooperates with a marker 152 formed along opening 101, e.g., along rim 111
and/or sidewalls 107, 109. Marker 152 is preferably on rim 111 along one or
both
sidewalls 107, 109, but could have other constructions. Marker 146 is
preferably a
ridge or some structure that is more than mere indicia so that it can be used
to
retighten lock 16 when wear begins to develop as well as at the time of
initial
tightening.
[72] When shaft 130 is turned and nut 136 drawn rearward, indicator 146
moves rearward (from the position in Fig. 16) with nut 136 within opening 101.
When indicator 146 aligns with marker 152 (Fig. 15), the operator knows that
tightening can be stopped. At this position, lock 16 applies a predetermined
pressure on wear member 14 irrespective of the wear on the nose and/or in the
socket 20. Hence, both under-tightening and over-tightening of the lock can be
easily avoided. As an alternative, indicator 146 can be omitted
and shaft 130
tightened to a predetermined amount of torque.
. CA 02880205 2015-01-28
[73] The various aspects of the invention are preferably used
together for
optimal performance and advantage. Nevertheless, the different aspects can be
used individually to provide the benefits they each provide.
21
